Thursday, November 1, 2012
The Blind Men and the Elephant
John Godfrey Saxe (1816-1887)
It was six men of Indostan
To learning much inclined,
Who went to see the Elephant
(Though all of them were blind),
That each by observation
Might satisfy his mind.
The First approached the Elephant,
And happening to fall
Against his broad and sturdy side,
At once began to bawl:
"God bless me! but the Elephant
Is very like a wall!"
The Second, feeling of the tusk,
Cried, "Ho, what have we here,
So very round and smooth and sharp?
To me 'tis mighty clear
This wonder of an Elephant
Is very like a spear!"
The Third approached the animal,
And happening to take
The squirming trunk within his hands,
Thus boldly up and spake:
"I see," quoth he, "the Elephant
Is very like a snake!"
The Fourth reached out an eager hand,
And felt about the knee
"What most this wondrous beast is like
Is mighty plain," quoth he:
"'Tis clear enough the Elephant
Is very like a tree!"
The Fifth, who chanced to touch the ear,
Said: "E'en the blindest man
Can tell what this resembles most;
Deny the fact who can,
This marvel of an Elephant
Is very like a fan!"
The Sixth no sooner had begun
About the beast to grope,
Than seizing on the swinging tail
That fell within his scope,
"I see," quoth he, "the Elephant
Is very like a rope!"
And so these men of Indostan
Disputed loud and long,
Each in his own opinion
Exceeding stiff and strong,
Though each was partly in the right,
And all were in the wrong!
So oft in theologic wars,
The disputants, I ween,
Rail on in utter ignorance
Of what each other mean,
And prate about an Elephant
Not one of them has seen!
This poem is just one version of the popular Bind Men and an Elephant story. There are many conclusions that you can draw from the story, but this version captures the idea that you can't properly understand something unless you have seen it in its entirety.
Similar arguments occur among data center operations teams advocating for different performance monitoring technologies such as NetFlow, IPFIX, SNMP, WMI, JMX, libvirt etc. Many of these arguments arise because teams are siloed, with each group arguing from their narrow perspective and dismissing the concerns of other teams. While narrowly focussed tools have their place, they miss the big picture.
Cloud-based architectures tightly couple network, storage and compute resources into a large scale, flexible, platform for delivering application services. The article, System boundary, describes the need for a holistic approach to organizing and managing data center resources. A comprehensive, cloud-oriented, approach to monitoring is essential for troubleshoot performance problems, automating operations and fully exploiting the potential of cloud architectures to increase efficiency by adapting to changing demand.
The sFlow standard addresses the challenge of cloud monitoring by embedding instrumentation throughout the cloud infrastructure in order to provide a comprehensive, real-time, view of the performance of all the individual network, server and application resources as well as the cloud as a whole. The sFlow architecture is designed to see elephants, not just individual body parts. It's only by gaining this comprehensive view of performance that large scale cloud data center environments can be properly understood and managed.